Auckland Police investigating knockout punch on a woman in McDonald's carpark

The woman was taken to Middlemore Hospital in a moderate condition.

Auckland Police are investigating a fight outside Westfield Manukau McDonald's in the early hours of Saturday morning where a woman was knocked out.

Video footage shows a man in a red hat striking the woman with such force that her head rocks back and she crashes onto the ground.

"One female was reportedly punched in the head and fell over," a police spokesperson said in a statement.

"She appeared to have lost consciousness for a time but regained it and was taken to Middlemore Hospital in a moderate condition."

The person who captured the fight on camera appears to be the only person who checked on the woman's condition.

The end of the footage shows the woman lying prone while the person taking the video asks repeatedly "Are you okay? Are you okay?"

Police spoke to those at the scene and are still making inquiries.

Footage of the fight was posted to Facebook, the caption claiming the puncher had earlier attempted to break up a fight between two women. He retaliated when he was struck in the back of the head, the caption said.

The woman was knocked out by a brutal left-hand punch.

The attacker was quickly swamped by other people at the scene who pulled him away from the women he attacked.

Another man grabs the attacker from behind and pulls him away. Meanwhile, a third woman attempts to throw punches at the man in the red hat.

The police spokesperson said they received a report of the fight early yesterday morning in the carpark of the Westfield Manukau McDonald's.

"Police spoke with people present at the scene and are continuing to make inquiries into what happened," the spokesperson said.